1. Department of Gastroenterology, Portuguese Oncology Institute of Porto, Porto, Portugal
2. Department of Gastroenterology, Instituto Português de Oncologia de Lisboa Francisco Gentil EPE, Lisbon, Portugal
3. University of Kansas School of Medicine, Kansas City, KS, USA
4. Division of Gastroenterology, Veterans Affairs Medical Center, Kansas City, KS, USA
5. Faculty of Medicine, CINTESIS (Center for Health Technology and Services Research), University of Porto, Porto, Portugal